Both genetic and lifestyle factors are instrumental in the development of diabetes. The most important blood parameter for tracking the course of the disease is glycohemoglobin (HbA1C). Researchers at the Helmholtz Zentrum München have now identified new gene variants that influence the concentration of HbA1C. Seven of the affected gene loci are linked to rare hereditary illnesses such as anaemias and iron storage disorders. For their study the researchers examined the data of 46,000 people and discovered that common gene variants influence the biology of the red blood cells, making a small yet quantifiable contribution to the diagnosis of diabetes. A more precise understanding of the genetic foundations and causes of the disease can lead to more promising treatments.